Ivan Husu

Influence of Cardiolipin on the Reaction Centre Protein: a Case Study About Lipid-membrane Protein Interactions in the Frame of Photosynthesis Ivan Husu

As well as other processes, in order to occur photosynthesis requires boundary membranes with both structural and functional roles. From the introduction of the fluid mosaic model (1972) knowledges on structure/function/dynamics of biomembranes largely evolved. Membranes are now described as microcosms where lipid-protein interactions give rise to well distinguished functional bilayer domains. Here experimental evidences are provided for interactions between the lipid cardiolipin (CL) and an integral photosynthetic protein, the Reaction Centre (RC) from purple bacteria. As minimum unit able to convert light into chemical energy, RC has been the first integral protein ever crystallised and structurally resolved (1984). Recent progresses (2000s) revealed the presence of CL and other lipids bound to the protein surface. In this view, results from laser spectroscopic studies of RCs reconstituted in micelles/liposomes are interpreted at molecular level according to an original kinetic model of the CL-RC system. Investigating the consequences of lipid-RC interactions may offer advantages in the approach to eukaryotic Photosystem complexes, successfully crystallised only in last years.